# 注意“你会看到”部分，我用了 cat，这是一种把文件打印到屏幕的简单办法，你可以输入 man cat 来看看关于这个命令的作用。
"""             Non-ASCII characters (with the high bit set) are printed as `M-' (for meta) followed by the character for the low 7 bits.
:...skipping...

CAT(1)                    BSD General Commands Manual                   CAT(1)

NAME
     cat -- concatenate and print files

SYNOPSIS
     cat [-benstuv] [file ...]

DESCRIPTION
     The cat utility reads files sequentially, writing them to the standard output.  The file operands are processed in command-line order.  If file is a single dash
     (`-') or absent, cat reads from the standard input.  If file is a UNIX domain socket, cat connects to it and then reads it until EOF.  This complements the UNIX
     domain binding capability available in inetd(8).

     The options are as follows:

     -b      Number the non-blank output lines, starting at 1.

     -e      Display non-printing characters (see the -v option), and display a dollar sign (`$') at the end of each line.

     -n      Number the output lines, starting at 1.

     -s      Squeeze multiple adjacent empty lines, causing the output to be single spaced.

     -t      Display non-printing characters (see the -v option), and display tab characters as `^I'.

     -u      Disable output buffering.

     -v      Display non-printing characters so they are visible.  Control characters print as `^X' for control-X; the delete character (octal 0177) prints as `^?'.
             Non-ASCII characters (with the high bit set) are printed as `M-' (for meta) followed by the character for the low 7 bits.

:
"""